Coil component

Abstract

To provide a coil component which can improve fixing strength between a core and an outer packaging.SOLUTION: A coil component 1 has: a core 20 having a core part 21 and a flange part 22 which is formed at one end in an axial direction of the core part 21; a wire 10 which has a winding part 11 provided on the core part 21; and an outer packaging 30 which includes magnetic particles and resin having different average particle diameters. The outer packaging 30 has: a body 31 which covers at least the core part 21 and the winding part 11; and a coating part 32 which bulges from an outer end surface 22a of the flange part 22 so as to overlap the outer end surface 22a when viewed from the axial direction. On a cross section of the outer packaging 30, the coating part 32 has a higher area ratio of the magnetic particles with a smaller average particle diameter, compared with the body 31.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a coil component. [Background technology]

[0002] Patent Document 1 discloses a technique relating to a surface-mounted coil component that can be used, for example, as an inductor. The coil component of Patent Document 1 has a core, a coil, and an exterior body. The core has a core portion for mounting the coil and a flange portion formed at one axial end of the core portion. The exterior body covers at least the core portion and the coil. In the coil component of Patent Document 1, a part of the exterior body covers the outer end surface of the flange portion (the surface opposite to the inner end surface of the flange portion (the surface to which the core portion is connected)). This makes it possible to prevent the core from coming loose from the exterior body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2017-510072 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in order to effectively prevent the core from coming loose from the exterior body, there is a need for a technique for further increasing the fixing strength between the core and the exterior body.

[0005] The present disclosure provides a coil component that can increase the fixing strength between a core and an outer casing. [Means for solving the problem]

[0006] A coil component according to an embodiment of the present disclosure includes: a core having a core portion and a flange portion formed at one end in the axial direction of the core portion; a wire having a winding portion provided on the core; an outer casing including magnetic particles having different average particle sizes and a resin; the exterior body includes a main body portion that covers at least the core portion and the winding portion, and a covering portion that protrudes from an outer end surface of the flange portion and overlaps the outer end surface when viewed in the axial direction, In a cross section of the exterior body, the magnetic particles having a small average particle size have a higher area ratio in the coating portion than in the main body portion.

[0007] In a coil component according to an embodiment of the present disclosure, the outer casing includes a main body portion that covers at least the core portion and the winding portion, and a covering portion that protrudes from the outer end surface of the flange portion and overlaps the outer end surface of the core portion when viewed in the axial direction. Because the covering portion covers the outer end surface of the flange, it serves as a stopper (a retainer) that secures the core to the main body portion. This increases the fixing strength (connection strength) between the core and the outer casing, making it less likely for the core to peel off from the outer casing.

[0008] Furthermore, in a coil component according to an embodiment of the present disclosure, the cross section of the outer casing has a higher area ratio of magnetic particles with a smaller average particle size in the coating than in the main body. This allows the magnetic particles in the coating to easily penetrate the irregularities formed on the outer end surface of the flange, and the coating is fixed (connected) to the flange via the magnetic particles that have penetrated the irregularities. This increases the fixing strength (connection strength) between the flange and the coating, making it even more difficult for the core to peel off from the outer casing.

[0009] The outer casing may have a peripheral portion that protrudes relative to the outer end surface of the flange portion and does not overlap with the outer end surface when viewed from the axial direction, and in the cross section of the outer casing, the covering portion may have a higher area proportion of magnetic particles having a smaller average particle size than the peripheral portion.

[0010] The flange portion may have an inner end surface facing the outer end surface along the axial direction, a side surface connecting the inner end surface and the outer end surface, and a chamfered portion formed on a ridge portion between the outer end surface and the side surface.

[0011] The coating portion may have a small particle size region and a large particle size region, the small particle size region not overlapping with the chamfered portion when viewed from the axial direction, and the large particle size region overlapping with the chamfered portion when viewed from the axial direction, and the large particle size region may have a higher area proportion of the magnetic particles having a larger average particle size than the small particle size region.

[0012] In the radial direction of the flange portion, the small grain size region may be located more inward of the outer end surface than the large grain size region.

[0013] The core may be a sintered core having pores.

[0014] The coating may include the magnetic particles having an average particle size that allows them to enter the pores.

[0015] The outer end surface may have a surface roughness smaller than a surface roughness of the covering portion.

[0016] The coil component may further have a first terminal electrode and a second terminal electrode provided on at least the outer end surface, the wire may have a first lead-out portion drawn from the winding portion and connected to the first terminal electrode, and a second lead-out portion drawn from the winding portion and connected to the second terminal electrode, and the covering portion may be located in an inter-electrode region between at least the first terminal electrode and the second terminal electrode. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view of an example of a coil component according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing the internal configuration of the coil component of FIG. [Figure 3] FIG. 3 is a perspective view of the core and wire shown in FIG. [Figure 4] FIG. 4 is a perspective view of the coil component shown in FIG. 1 as viewed from the mounting surface side. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV of the coil device shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI of the coil device shown in FIG. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a portion of the coil component shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view of the coil component according to the second embodiment. [Figure 9] FIG. 9 is a cross-sectional view of the coil device shown in FIG. 8 as viewed from the X-axis direction. [Figure 10] FIG. 10 is a plan view of a modified example of the coil device shown in FIG. [Figure 11] FIG. 11 is a plan view of a modified example of the coil device shown in FIG. [Figure 12] FIG. 12 is a cross-sectional view of a modified example of the coil device shown in FIG. [Figure 13] FIG. 13 is a perspective view of a modified example of the coil device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the contents shown in the drawings are merely schematic and illustrative for understanding the present disclosure, and the appearance and dimensional ratios may differ from the actual product. Furthermore, the present disclosure is not limited to the following embodiments.

[0019] First embodiment A coil component 1 according to a first embodiment shown in Fig. 1 functions as, for example, an inductor and is mounted in the power supplies of various electrical devices. As shown in Fig. 2, the coil component 1 includes an element body 2, a wire 10, and terminal electrodes 40a and 40b. The coil component 1 is a surface-mount type coil component.

[0020] The element body 2 has a core 20 and an outer casing 30. The element body 2 is a hexahedron, but may be another polyhedron such as an octahedron. The element body 2 has a first surface 30a on which the terminal electrodes 40a and 40b are arranged, a second surface 30b opposite the first surface 30a, and one or more connection surfaces connecting the first surface 30a and the second surface 30b. In this embodiment, the element body 2 is a hexahedron. Therefore, the element body 2 has a third surface 30c, a fourth surface 30d adjacent to the third surface 30c, a fifth surface 30e adjacent to the fourth surface 30d, and a sixth surface 30f adjacent to the fifth surface 30e as connection surfaces connecting the first surface 30a and the second surface 30b.

[0021] In FIG. 2 and other figures, the X-axis is the axis corresponding to the direction in which the fourth surface 30d and the sixth surface 30f face each other. The Y-axis is the axis corresponding to the direction in which the third surface 30c and the fifth surface 30e face each other. The Z-axis is the axis corresponding to the direction in which the first surface 30a and the second surface 30b face each other. The X-axis, Y-axis, and Z-axis are perpendicular to each other. Hereinafter, for each of the X-axis, Y-axis, and Z-axis, the direction away from the center of the element body 2 is referred to as the outward direction, and the direction toward the center of the element body 2 is referred to as the inward direction. The positive side of the Z-axis is referred to as the upper side (upward), and the negative side of the Z-axis is referred to as the lower side (downward). However, the upper side in the Z-axis direction does not necessarily coincide with the upper side in the vertical direction. The lower side in the Z-axis direction does not necessarily coincide with the lower side in the vertical direction.

[0022] In the present disclosure, "equal," "the same," "equivalent," or "similar" does not only refer to a state in which the physical quantities of multiple objects being compared are exactly equal, identical, equivalent, or "similar," but also includes a state in which there is an error of ±Δ% or less (not particularly limited, for example, Δ=7, 5, or 3) between the physical quantities of multiple objects being compared.

[0023] Furthermore, in the present disclosure, "parallel" does not only refer to strict parallelism, but also includes a state in which there is an error of ±Δθ° (not particularly limited, for example, Δθ=3) or less from strict parallelism. Furthermore, "perpendicular" or "orthogonal" does not only refer to strict perpendicular or orthogonal, but also includes a state in which there is an error of ±Δθ° (not particularly limited, for example, Δθ=3) or less from strict perpendicular or orthogonal.

[0024] The length of the element body 2 in the X-axis direction is not particularly limited, but is, for example, 0.6 to 6.5 mm. The length of the element body 2 in the Y-axis direction is not particularly limited, but is, for example, 0.6 to 6.5 mm. The length of the element body 2 in the Z-axis direction is not particularly limited, but is, for example, 0.5 to 5.0 mm.

[0025] 1, the second surface 30b, the third surface 30c, the fourth surface 30d, the fifth surface 30e, and the sixth surface 30f are formed by the exterior body 30. On the other hand, as shown in Fig. 4, the first surface 30a is formed by the outer end surface 22a of the core 20 and a part of the exterior body 30 located around the outer end surface 22a, and forms the mounting surface of the element body 2. The mounting surface is the surface that faces a mounting board (not shown) when the coil component 1 is mounted on the mounting board.

[0026] The element body 2 is not limited to a polyhedron, and may be a cylindrical body such as a cylinder from the viewpoint of effective magnetic flux. In the present disclosure, a cylinder also includes a solid body in which the first surface 30a and the second surface 30b are not congruent, such as a truncated cone. When the element body 2 is a cylinder or a truncated cone, the element body 2 is provided with one connecting surface that connects the first surface 30a and the second surface 30b.

[0027] The element body 2 is formed, for example, by pouring the exterior material that constitutes the exterior body 30 into the cavity of a mold in which the core 20 is placed, and then compressing and curing the poured material. The exterior material (exterior body 30) is made of a composite material containing magnetic particles (magnetic filler) and resin. In particular, in this embodiment, the exterior material contains magnetic particles (magnetic powder) having different average particle sizes. The element body 2 can also be formed by resin molding, transfer molding, injection molding, dry molding, etc.

[0028] The particle size of the magnetic particles constituting the exterior material is not particularly limited, but is, for example, 0.5 μm to 50 μm. The magnetic material (magnetic filler) constituting the exterior material is not particularly limited, but is, for example, ferrite or a metal magnetic material. Examples of metal magnetic materials include, but are not particularly limited to, soft magnetic metal magnetic materials such as sendust (Fe-Si-Al; iron-silicon-aluminum), Fe-Si-Cr (iron-silicon-chromium), Fe-C-Si, Fe-Cr-Al, permalloy (Fe-Ni), Fe-Ni-Al, Fe-Ni-Mo, carbonyl iron-based, carbonyl Ni-based, amorphous powder, and nanocrystal powder. Examples of ferrite include Mn-Zn and Ni-Cu-Zn. The resin constituting the exterior material is not particularly limited, but is, for example, epoxy resin, phenol resin, acrylic resin, polyester resin, polyimide, polyamide-imide, silicone resin, or a combination thereof. The relative permeability of the exterior body 30 is not particularly limited, but is, for example, 1 to 20,000.

[0029] 1, the third surface 30c, the fourth surface 30d, the fifth surface 30e, and the sixth surface 30f are inclined surfaces that form an acute angle with the first surface 30a. However, the third surface 30c, the fourth surface 30d, the fifth surface 30e, and the sixth surface 30f may be perpendicular to the first surface 30a.

[0030] Curved portions are formed at the ridgeline between the third surface 30c and the fourth surface 30d, the ridgeline between the fourth surface 30d and the fifth surface 30e, the ridgeline between the fifth surface 30e and the sixth surface 30f, and the ridgeline between the sixth surface 30f and the third surface 30c. The curved portions are curved in a cross section perpendicular to the direction orthogonal to the first surface 30a (the Z-axis direction). These curved portions are not essential and may be omitted.

[0031] As shown in FIG. 2 , the core 20 has a core portion 21 and a flange portion 22. The core 20 is a T-shaped core and is made of a sintered body (sintered core). The core 20 (core portion 21 and / or flange portion 22) has holes. The core 20 may be made of a composite material containing a magnetic material and a resin. The core 20 may also be formed by, for example, powder compaction, injection molding, or cutting. The material (magnetic material and / or resin) making up the core 20 may be the same as or different from the material making up the exterior body 30. The relative magnetic permeability of the core 20 may be the same as or different from the relative magnetic permeability of the exterior body 30. For example, the core 20 may be made of a material having a higher relative magnetic permeability than the exterior body 30.

[0032] Core portion 21 has a cylindrical shape and protrudes from the center of flange portion 22. The axial direction of core portion 21 corresponds to the Z-axis direction. The axial direction of core portion 21 also corresponds to the winding axis direction of winding portion 11. Core portion 21 may protrude from the center of flange portion 22 at a position offset in the radial direction thereof. Core portion 21 is located inside exterior body 30. The shape of core portion 21 may be, for example, a square prism, an octagonal prism, or any other polygonal prism.

[0033] The flange 22 has a flat rectangular parallelepiped shape (flat plate shape) and is formed at one axial end of the core 21. The flange 22 has an outer end face 22a, an inner end face 22b, and a side face 22c. The inner end face 22b is a face connected to the core 21. The outer end face 22a is a face opposite the inner end face 22b. The side face 22c is a face connecting the outer end face 22a and the inner end face 22b. The flange 22 is disposed parallel to the second face 30b of the exterior body 30. The planar shape of the flange 22 may be, for example, a circle, an octagon, or another polygon.

[0034] As shown in FIG. 4, the outer end surface 22a of the flange portion 22 is partially exposed on the first surface 30a. A terminal electrode 40a is provided on one side of the outer end surface 22a in the X-axis direction, and a terminal electrode 40b is provided on the other side of the outer end surface 22a in the X-axis direction. As indicated by the dashed lines in FIG. 4, the flange portion 22 has an electrode contact portion 36a located on one side of the outer end surface 22a in the X-axis direction and an electrode contact portion 36b located on the other side of the outer end surface 22a in the X-axis direction. The electrode contact portion 36a is the contact surface between the terminal electrode 40a and the outer end surface 22a, and the terminal electrode 40a is in contact with the electrode contact portion 36a. The electrode contact portion 36b is the contact surface between the terminal electrode 40b and the outer end surface 22a, and the terminal electrode 40b is in contact with the electrode contact portion 36b.

[0035] The thermal expansion coefficient of the core 20 (at least one of the flange 22 and the core 21) may be equal to or different from the thermal expansion coefficient of the exterior body 30. The thermal expansion coefficient of the core 20 (at least one of the flange 22 and the core 21) may be smaller than or larger than the thermal expansion coefficient of the exterior body 30.

[0036] When the core portion 21 is formed of an annealed metal, the thermal expansion coefficient of the core portion 21 is, for example, 10 ppm / K or more and 20 ppm / K or less. When the core portion 21 is formed of a composite material containing a magnetic material and a resin, the thermal expansion coefficient of the core portion 21 is, for example, 20 ppm / K or more and 60 ppm / K or less. The thermal expansion coefficient of the exterior body 30 is, for example, 15 ppm / K. The difference between the thermal expansion coefficient of the core portion 21 and the thermal expansion coefficient of the exterior body 30 may be, for example, 2 ppm / K or more, or 5 ppm / K or more. The difference between the thermal expansion coefficient of the core portion 21 and the thermal expansion coefficient of the exterior body 30 may be, for example, 45 ppm / K or less, or 10 ppm / K or less. In this case, it is possible to prevent cracks from occurring in the exterior body 30 around the core portion 21 due to the thermal expansion coefficient of the core portion 21.

[0037] An example of a method for making the thermal expansion coefficient of core portion 21 smaller than that of outer casing 30 is to anneal core portion 21. When core portion 21 contains magnetic particles and resin, annealing core portion 21 reduces the resin content, thereby reducing the thermal expansion coefficient of core portion 21.

[0038] Note that the thermal expansion coefficient of core portion 21 may be made smaller than that of exterior body 30 by forming core 20 from a material different from that of exterior body 30. Alternatively, in the case where core 20 and exterior body 30 both contain magnetic particles and resin, the thermal expansion coefficient of core portion 21 may be made smaller than that of exterior body 30 by making the blending ratio of resin in core 20 smaller than that of resin in exterior body 30. Alternatively, the thermal expansion coefficient of core portion 21 may be made smaller than that of exterior body 30 by forming core 20 (core portion 21 and / or flange portion 22) from ceramics such as sintered ferrite.

[0039] As shown in FIG. 2, the wire 10 has a winding portion 11 wound into a coil shape and lead portions 12a and 12b drawn out from the winding portion 11. The winding portion 11 is located inside the outer casing 30 and is provided on the outer circumferential surface of the core portion 21. The winding portion 11 is formed, for example, by winding a wire around the core portion 21. However, if the winding portion 11 is an air-core coil, the winding portion 11 may be fitted into the core portion 21. The wire forming the winding portion 11 can be, for example, a conductive core wire made of copper or the like, such as a rectangular wire, a round wire, a twisted wire, a Litz wire, or a braided wire, or an insulating-coated wire in which such a conductive core wire is covered with an insulating coating. Specifically, known winding wires such as AIW, UEW, PEW, and USTC can be used. The diameter of the wire is not particularly limited, but in the case of a round wire, it is, for example, 50 μm to 2 mm. In the case of a rectangular wire, for example, the wire thickness is 20 μm to 2 mm and the wire width is 40 μm to 2 mm. As shown in Fig. 3, the number of layers in the winding axis direction of the winding portion 11 is, for example, three, and the number of layers in the radial direction is, for example, three.

[0040] 2, lead-out portions 12a and 12b are drawn out from winding portion 11 and constitute one end and the other end of the wire that forms winding portion 11. Lead-out portion 12a is drawn out from one end of winding portion 11 in the Z-axis direction inside exterior body 30 toward third surface 30c of exterior body 30. Lead-out portion 12b is drawn out from the other end of winding portion 11 in the Z-axis direction inside exterior body 30 toward third surface 30c of exterior body 30.

[0041] As shown in FIG. 3, the terminal electrodes 40a and 40b are formed on the flange portion 22 and are spaced apart along the X-axis. The terminal electrodes 40a and 40b have an exposed portion 42 and buried portions 44 and 46. The exposed portion 42 is disposed on the outer end surface 22a and extends along the Y-axis. The shape of the exposed portion 42 is not particularly limited, but may be, for example, rectangular in plan view. At least a portion of the exposed portion 42 is exposed from the first surface 30a (see FIG. 4). The buried portions 44 and 46 are disposed on the side surface 22c and face each other along the Y-axis. The buried portion 44 extends upward from one longitudinal end of the exposed portion 42. The buried portion 46 extends upward from the other longitudinal end of the exposed portion 42.

[0042] The terminal electrode 40a is connected to the lead portion 12a, and the terminal electrode 40b is connected to the lead portion 12b. The lead portion 12a is connected to the embedded portion 44 of the terminal electrode 40a. The lead portion 12b is connected to the embedded portion 44 of the terminal electrode 40b. The terminal electrodes 40a and 40b are formed, for example, by a laminated electrode film made of a base electrode film and a plating film formed on the base electrode film. The base electrode film is a conductive paste film containing, but is not limited to, a metal such as Sn, Ag, Ni, Cu, or Pd, or an alloy thereof. The plating film is, but is not limited to, a metal such as Sn, Au, Ni, Pt, Ag, Pd, or Cu, or an alloy thereof.

[0043] As shown in Fig. 5, the thickness of the terminal electrode 40a in its cross section becomes thinner toward the outer edge of the terminal electrode 40a and becomes thicker toward the center of the terminal electrode 40a. The cross section of the terminal electrode 40a has a convex shape that protrudes downward. The same is true for the cross section of the terminal electrode 40b. However, the cross section shapes of the terminal electrodes 40a and 40b are not limited to the shape shown in Fig. 5. For example, the cross section shapes of the terminal electrodes 40a and 40b may be rectangular.

[0044] As shown in FIG. 6, the thickness of the terminal electrode 40a in its longitudinal cross section becomes thinner toward the outer edge of the terminal electrode 40a and becomes thicker toward the center of the terminal electrode 40a. The longitudinal cross section of the terminal electrode 40a has a convex shape that protrudes downward. The same is true for the longitudinal cross section of the terminal electrode 40b. However, the longitudinal cross sections of the terminal electrodes 40a and 40b are not limited to the shape shown in FIG. 6. For example, the longitudinal cross sections of the terminal electrodes 40a and 40b may be rectangular.

[0045] 5, the thickness T of each of the terminal electrodes 40a and 40b is, for example, 3 μm to 100 μm. The thickness of the terminal electrode 40a is the same as the thickness of the terminal electrode 40b, but they may be different. The lead portion 12a is connected to the terminal electrode 40a by, for example, thermocompression bonding, soldering, or a conductive adhesive. The lead portion 12b is connected to the terminal electrode 40b by, for example, thermocompression bonding, soldering, or a conductive adhesive.

[0046] 4, the outer periphery of the exposed portion 42 of the terminal electrode 40a has a first side 41a1, a second side 41a2, a third side 41a3, and a fourth side 41a4. The first side 41a1 and the second side 41a2 extend parallel to each other along the X-axis, but may extend non-parallel to each other. The third side 41a3 and the fourth side 41a4 extend parallel to each other along the Y-axis, but may extend non-parallel to each other.

[0047] The outer periphery of the exposed portion 42 of the terminal electrode 40b has a first side 41b1, a second side 41b2, a third side 41b3, and a fourth side 41b4. The first side 41b1 and the second side 41b2 extend parallel to each other along the X-axis, but may extend non-parallel to each other. The third side 41b3 and the fourth side 41b4 extend parallel to each other along the Y-axis, but may extend non-parallel to each other.

[0048] The first side 41a1, the second side 41a2, and the third side 41a3 are located on the outer edge of the first surface 30a. The first side 41b1, the second side 41b2, and the third side 41b3 are located on the outer edge of the first surface 30a. Here, the outer edge of the first surface 30a includes the outer periphery of the first surface 30a and the peripheral portion of the outer periphery of the first surface 30a. The peripheral portion of the outer periphery of the first surface 30a is the region between a first position on the outer periphery of the first surface 30a and a second position spaced a predetermined distance inward from the first position in the X-axis direction or the Y-axis direction (however, if the shape of the first surface 30a is circular or elliptical, for example). Here, "inward" refers to the direction toward the center of the first surface 30a. Furthermore, the specified length is, for example, a length equivalent to 30% or less of the length of the first surface 30a in the X-axis direction or the Y-axis direction (however, if the shape of the first surface 30a is circular or elliptical, the diameter, major axis, or minor axis).

[0049] The outer edge of the first surface 30a includes a first outer edge 2b1, a second outer edge 2b2, a third outer edge 2b3, and a fourth outer edge 2b4. The first outer edge 2b1 and the second outer edge 2b2 extend parallel to each other along the X-axis, but may extend non-parallel to each other. The third outer edge 2b3 and the fourth outer edge 2b4 extend parallel to each other along the Y-axis, but may extend non-parallel to each other.

[0050] As shown in Fig. 5, the exterior body 30 has a main body portion 31, a covering portion 32, and a peripheral portion 33. The main body portion 31 covers at least the core portion 21 and the winding portion 11. The main body portion 31 also covers at least a portion (the inner end surface 22b and the side surface 22c) of the flange portion 22. The surface roughness of the outer end surface 22a of the flange portion 22 is greater than the surface roughness of the covering portion 32. However, the surface roughness of the outer end surface 22a may be less than or equal to the surface roughness of the covering portion 32.

[0051] Both the covering portion 32 and the peripheral edge portion 33 protrude (project) from the outer end surface 22a of the flange portion 22. When viewed in the axial direction of the core portion 21 (i.e., the Z-axis direction), the covering portion 32 overlaps the outer end surface 22a of the flange portion 22. The covering portion 32 includes covering portions 32a, 32b, and 32c. As shown in FIG. 4, the covering portions 32a and 32b are formed in an inter-electrode region 35 between the terminal electrodes 40a and 40b.

[0052] Covering portion 32a is located on one side in the Y-axis direction of interelectrode region 35 (the third surface 30c side) and protrudes inward in the Y-axis direction from the outer edge of first surface 30a. Covering portion 32b is located on the other side in the Y-axis direction of interelectrode region 35 (the fifth surface 30e side) and protrudes inward in the Y-axis direction from the outer edge of first surface 30a. Covering portions 32a and 32b are arranged to face each other along the Y-axis.

[0053] Furthermore, the covering portion 32a physically connects the terminal electrodes 40a and 40b to each other so as to bridge the gap between the terminal electrodes 40a and 40b in the X-axis direction on one side of the interelectrode region 35 in the Y-axis direction. Furthermore, the covering portion 32b physically connects the terminal electrodes 40a and 40b to each other so as to bridge the gap between the terminal electrodes 40a and 40b in the X-axis direction on the other side of the interelectrode region 35 in the Y-axis direction.

[0054] The covering portion 32c is the portion of the covering portion 32 excluding the covering portions 32a and 32b, i.e., the portion not located in the inter-electrode region 35. As shown in FIG. 5, the covering portion 32c overlaps the outer edge of the terminal electrode 40a, for example, on one side in the X-axis direction. The covering portion 32c also overlaps the outer edge of the terminal electrode 40b, for example, on the other side in the X-axis direction. The covering portion 32c overlaps the first side 41a1, the second side 41a2, and the third side 41a3 of the terminal electrode 40a shown in FIG. 4. The covering portion 32c also overlaps the first side 41b1, the second side 41b2, and the third side 41b3 of the terminal electrode 40b.

[0055] 5, the covering portion 32b (similarly to the covering portion 32a) is raised relative to the electrode contact portion 36a and the electrode contact portion 36b. In particular, the covering portion 32b is raised relative to the outer edge portion of the electrode contact portion 36a (particularly the portion along the interelectrode region 35). Furthermore, the covering portion 32b is raised relative to the outer edge portion of the electrode contact portion 36b (particularly the portion along the interelectrode region 35).

[0056] Here, the outer edge of the electrode contact portion 36a includes the outer periphery of the electrode contact portion 36a and the peripheral portion of the outer periphery of the electrode contact portion 36a. The peripheral portion of the outer periphery of the electrode contact portion 36a is a region between a first position on the outer periphery of the electrode contact portion 36a and a second position spaced a predetermined length inward from the first position in the X-axis direction or the Y-axis direction (however, if the shape of the electrode contact portion 36a is circular or elliptical, for example, then the radial direction). The predetermined length is, for example, a length equivalent to 30% or less of the length of the electrode contact portion 36a in the X-axis direction or the Y-axis direction (however, if the shape of the electrode contact portion 36a is circular or elliptical, for example, then the diameter, major axis, or minor axis). The outer edge of the electrode contact portion 36b is defined in the same way as the outer edge of the electrode contact portion 36a.

[0057] The covering portion 32b (similarly to the covering portion 32a) is located below the average height position of the electrode contact portion 36a. In particular, the covering portion 32b is located below the average height position of the outer edge portion of the electrode contact portion 36a (particularly the portion along the interelectrode region 35). The covering portion 32b is also located below the average height position of the electrode contact portion 36b. In particular, the covering portion 32b is located below the average height position of the outer edge portion of the electrode contact portion 36b (particularly the portion along the interelectrode region 35). Note that the average height position refers to the average height position of the unevenness of the electrode contact portion 36a or 36b when the electrode contact portion 36a or 36b has unevenness.

[0058] As shown in FIG. 4, the covering portion 32a (and the covering portion 32b) partially covers the outer edge portion of the terminal electrode 40a (the portion along the inter-electrode region 35). The outer edge portion of the terminal electrode 40a includes the outer periphery of the terminal electrode 40a and the peripheral portion of the outer periphery of the terminal electrode 40a. The peripheral portion of the outer periphery of the terminal electrode 40a is the region between a first position on the outer periphery of the terminal electrode 40a and a second position that is spaced a predetermined length inward from the first position in the X-axis direction or the Y-axis direction (however, if the shape of the terminal electrode 40a is circular or elliptical, for example). The predetermined length is, for example, a length that corresponds to 30% or less of the length of the terminal electrode 40a in the X-axis direction or the Y-axis direction (however, if the shape of the terminal electrode 40a is circular or elliptical, for example, the diameter, major axis, or minor axis).

[0059] The covering portion 32a (and the covering portion 32b) partially covers the outer edge portion of the terminal electrode 40b (the portion along the inter-electrode region 35). The outer edge portion of the terminal electrode 40b includes the outer periphery of the terminal electrode 40b and the peripheral portion of the outer periphery of the terminal electrode 40b. The peripheral portion of the outer periphery of the terminal electrode 40b is the region between a first position on the outer periphery of the terminal electrode 40b and a second position that is spaced a predetermined length inward from the first position in the X-axis direction or the Y-axis direction (however, if the shape of the terminal electrode 40b is circular or elliptical, for example). The predetermined length is, for example, a length that corresponds to 30% or less of the length of the terminal electrode 40b in the X-axis direction or the Y-axis direction (however, if the shape of the terminal electrode 40b is circular or elliptical, for example, the diameter, major axis, or minor axis).

[0060] The covering portion 32a (similarly to the covering portion 32b) may cover the outer edge portion (the portion along the inter-electrode region 35) of either the terminal electrodes 40a or 40b.

[0061] The covering portions 32a and 32b are formed as follows. For example, when the element body 2 is molded, a part of the exterior material constituting the exterior body 30 is caused to flow from outside the side surface 22c of the flange portion 22 into the inter-electrode region 35 on the outer end surface 22a inside the mold. The exterior material that has flowed into the inter-electrode region 35 is compressed and hardened, thereby forming the covering portions 32a and 32b.

[0062] In the interelectrode region 35, the outer edge of the covering portion 32a (similarly for the covering portion 32b) extends along the outer periphery (fourth side 41a4) of the terminal electrode 40a and the outer periphery (fourth side 41b4) of the terminal electrode 40b. The covering portion 32a is formed in the interelectrode region 35 so as to reduce the step between the outer end surface 22a of the flange portion 22 and the surface of the terminal electrode 40a, and the step between the outer end surface 22a of the flange portion 22 and the surface of the terminal electrode 40b. The step between the surface of the covering portion 32a and the surface of the terminal electrode 40a, or the step between the surface of the covering portion 32a and the surface of the terminal electrode 40b, is 5 μm or less. The same applies to the step between the surface of the covering portion 32b and the surface of the terminal electrode 40a, or the step between the surface of the covering portion 32b and the surface of the terminal electrode 40b.

[0063] The coated portions 32a and 32b are spaced apart along the Y-axis, and for example, the coated portions 32a and 32b are not formed in the center of the interelectrode region 35 in the Y-axis direction. That is, the coated portions 32a and 32b are partially formed in the interelectrode region 35, and a portion of the outer end surface 22a is exposed between the coated portions 32a and 32b. The coated portions 32a and 32b may be formed over, for example, 10% or more of the interelectrode region 35, or over 30% or more of the interelectrode region 35, or over 50% or more of the interelectrode region 35, or over 70% or more of the interelectrode region 35. However, the coated portions 32a and 32b may be formed over the entire interelectrode region 35. In this case, the coated portions 32a and 32b are integrated to form a single coated portion.

[0064] Furthermore, one or more covering portions may be formed at any position in the interelectrode region 35. For example, two or more mutually discontinuous covering portions may be discretely arranged on one side or the other in the Y-axis direction of the interelectrode region 35. Furthermore, two or more covering portions 32a may protrude from the outer edge of the first surface 30a toward the interelectrode region 35, and two or more covering portions 32b may protrude from the outer edge of the first surface 30a toward the interelectrode region 35.

[0065] The maximum protrusion width of the covering portion 32a from the outer edge of the first surface 30a is the same as, but may be different from, the maximum protrusion width of the covering portion 32b from the outer edge of the first surface 30a. The protrusion width W1 (FIG. 7) of the covering portion 32a from the side surface 22c of the flange portion 22 is not particularly limited, but is less than ½, ⅓, ¼, or ⅕ of the width W2 (FIG. 3) of the flange portion 22 in the Y-axis direction. The same applies to the covering portion 32b. The covering portions 32a and 32b may protrude from the outer edge of the first surface 30a to the center of the interelectrode region 35 in the Y-axis direction. However, the center of the interelectrode region 35 in the Y-axis direction has a width of ±Δw in the Y-axis direction relative to the center of the interelectrode region 35 in the Y-axis direction. Δw is, for example, a width equivalent to 10% or less of the length of the interelectrode region 35 in the Y-axis direction. The end portion of the inter-electrode region 35 in the Y-axis direction is a region having a predetermined width in the Y-axis direction (for example, a width equivalent to 20% or less of the length of the inter-electrode region 35 in the Y-axis direction).

[0066] As shown in Fig. 5, the peripheral edge portion 33 does not overlap the outer end surface 22a of the flange portion 22 when viewed in the axial direction of the core portion 21 (i.e., the Z-axis direction). The peripheral edge portion 33 is continuous with the covering portions 32a to 32c. The peripheral edge portion 33 protrudes downward relative to the electrode contact portions 36a and 36b. In particular, the peripheral edge portion 33 protrudes downward relative to the outer edges of the electrode contact portions 36a and 36b (particularly the portions along the first outer edge portion 2b1 to the fourth outer edge portion 2b4 of the first surface 30a shown in Fig. 4).

[0067] The peripheral edge 33 is located below the average height position of the electrode contact portions 36a and 36b. In particular, the peripheral edge 33 is located below the average height position of the outer edges of the electrode contact portions 36a and 36b (particularly, the portions along the first outer edge 2b1 to the fourth outer edge 2b4 of the first surface 30a).

[0068] As shown in FIG. 4, the peripheral edge 33 is located at the outer edge of the first surface 30a. When viewed from the Z-axis direction, the peripheral edge 33 extends along the outer periphery of the outer end surface 22a (FIG. 2) so as to surround the outer end surface 22a. In this embodiment, the peripheral edge 33 is located at the first outer edge 2b1, the second outer edge 2b2, the third outer edge 2b3, and the fourth outer edge 2b4. However, the peripheral edge 33 may be located at any one, two, or three of the first outer edge 2b1, the second outer edge 2b2, the third outer edge 2b3, and the fourth outer edge 2b4.

[0069] The peripheral edge portion 33 is formed along the X-axis over the entire first outer edge portion 2b1, but may be formed locally on a portion of the first outer edge portion 2b1. Similarly, the peripheral edge portion 33 is formed along the X-axis over the entire second outer edge portion 2b2, but may be formed locally on a portion of the second outer edge portion 2b2. Furthermore, the peripheral edge portion 33 is formed along the Y-axis over the entire third outer edge portion 2b3, but may be formed locally on a portion of the third outer edge portion 2b3. Similarly, the peripheral edge portion 33 is formed along the Y-axis over the entire fourth outer edge portion 2b4, but may be formed locally on a portion of the fourth outer edge portion 2b4.

[0070] As shown in FIG. 5 , the peripheral edge 33 is formed by extending a portion of the exterior body 30 at the outer edge of the first surface 30a downward from the height position of the outer end surface 22a (electrode contact portions 36a and 36b, particularly the outer edges of the electrode contact portions 36a and 36b). For example, during molding of the element body 2, a portion of the exterior material constituting the exterior body 30 is caused to extend from the outside of the side surface 22c of the flange portion 22 to a position below the height position of the outer end surface 22a within the mold. The exterior material that has extended below the height position of the outer end surface 22a is compressed and hardened, thereby forming the peripheral edge 33. The height Ha from the second surface 30b to the lower end of the peripheral edge 33 is greater than the height Hb from the second surface 30b to the electrode contact portion 36a or 36b (particularly the outer edge of the electrode contact portion 36a or 36b).

[0071] The height (average height or maximum height) Hc1 of the covering portion 32b (similarly for the covering portion 32a) from the electrode contact portion 36a is smaller than the thickness (maximum thickness) T of the terminal electrode 40a. However, the height Hc1 of the covering portion 32b from the electrode contact portion 36a may be equal to the thickness T of the terminal electrode 40a. The thickness (maximum thickness) T of the terminal electrode 40a or 40b is not particularly limited, but is 10 μm or greater. The same applies to the height of the covering portion 32b from the electrode contact portion 36b.

[0072] The height (average height or maximum height) Hc2 of the peripheral edge 33 from the electrode contact portion 36a is smaller than the thickness (maximum thickness) T of the terminal electrode 40a. However, the height Hc2 of the peripheral edge 33 from the electrode contact portion 36a may be equal to the thickness T of the terminal electrode 40a. The same applies to the height of the peripheral edge 33 from the electrode contact portion 36b.

[0073] The height (average height or maximum height) of the covering portion 32b (similarly for the covering portion 32a) from the electrode contact portion 36a is lower than the height (average height or maximum height) of the peripheral portion 33 from the electrode contact portion 36a, but it may be equal to this. The height Hc1 of the covering portion 32b from the electrode contact portion 36a is not particularly limited, but is, for example, 2 / 3 or less of the thickness (maximum thickness) T of the terminal electrode 40a. The same applies to the height of the covering portion 32b from the electrode contact portion 36b.

[0074] The height (average height or maximum height) Hc1 of the covering portion 32b (similarly for the covering portion 32a) from the electrode contact portion 36a is greater than the thickness (average thickness or maximum thickness) of the outer edge portion of the terminal electrode 40a (particularly the portion along the interelectrode region 35). However, the height Hc1 of the covering portion 32b from the electrode contact portion 36a may be equal to the thickness of the outer edge portion of the terminal electrode 40a. The same applies to the height of the covering portion 32b from the electrode contact portion 36b.

[0075] Furthermore, the height (average height or maximum height) Hc2 of the peripheral edge 33 from the electrode contact portion 36a is greater than the thickness (average thickness or maximum thickness) of the outer edge of the terminal electrode 40a (particularly the portions along the first outer edge 2b1, second outer edge 2b2, and third outer edge 2b3 of the first surface 30a in FIG. 4). However, the height Hc2 of the peripheral edge 33 from the electrode contact portion 36a may be equal to the thickness of the outer edge of the terminal electrode 40a. The same applies to the height of the peripheral edge 33 from the electrode contact portion 36b.

[0076] The height Hc1 of the covering portions 32a and 32b from the electrode contact portion 36a does not necessarily have to be constant and may have a distribution. Furthermore, the height Hc2 of the peripheral portion 33 from the electrode contact portion 36a does not necessarily have to be constant and may have a distribution. The surfaces of the covering portions 32a to 32c and the peripheral portion 33 do not necessarily have to be flat and may be inclined, convex, concave, or uneven.

[0077] 7 , the exterior housing 30 includes first magnetic particles (small particles) 37 having a relatively small average particle size, second magnetic particles (large particles) 38 having a relatively large average particle size, and third magnetic particles (medium particles) 39 having an average particle size between the average particle sizes of the first magnetic particles 37 and the second magnetic particles 38. The inclusion of the large second magnetic particles 38 in the exterior housing 30 increases the inductance value of the coil device 1. Furthermore, during compression molding of the exterior material that constitutes the exterior housing 30, the small second magnetic particles 37 and / or the medium third magnetic particles 39 enter between the large second magnetic particles 38 together with the resin, thereby increasing the packing density of the magnetic particles in the exterior housing 30 and increasing the magnetic permeability of the exterior housing 30.

[0078] In this embodiment, the first magnetic particles 37, the second magnetic particles 38, and the third magnetic particles 39 are all metal magnetic particles. The first magnetic particles 37, the second magnetic particles 38, and the third magnetic particles 39 may have an insulating film covering the metal magnetic particles. The insulating film is not particularly limited, but examples include metal oxide coatings, resin coatings, and chemical conversion films of phosphorus, zinc, etc. The thickness of the insulating film is several nanometers to several tens of nanometers. By covering the metal magnetic particles with an insulating film, it is possible to increase the insulation resistance and withstand voltage.

[0079] The average particle size of the first magnetic particles 37 is not particularly limited, but is, for example, 0.5 μm or more and 10 μm or less. The average particle size of the first magnetic particles 37 is smaller than the thickness of the terminal electrode 40a or 40b. The average particle size of the first magnetic particles 37 may be smaller than the thickness of the coating portion 32 (coating portion 32a, 32b, or 32c).

[0080] The average particle size of the second magnetic particles 38 is not particularly limited, but is, for example, greater than 20 μm and equal to or less than 100 μm. The average particle size of the second magnetic particles 38 is equal to or greater than the thickness of the terminal electrode 40a or 40b. The average particle size of the second magnetic particles 38 may be equal to or greater than the thickness of the coating portion 32 (coating portion 32a, 32b, or 32c).

[0081] The average particle size of the third magnetic particles 39 is, for example, greater than 10 μm and equal to or less than 20 μm, or greater than 10 μm and equal to or less than 30 μm. The average particle size of the third magnetic particles 39 is smaller than the thickness of the terminal electrode 40a or 40b, but may be equal to or greater than the thickness of the terminal electrode 40a or 40b. The average particle size of the third magnetic particles 39 may also be smaller than the thickness of the coating 32 (coating 32a, 32b, or 32c), or may be equal to or greater than the thickness of the coating 32.

[0082] The first magnetic particles 37 may have an average particle size that allows them to enter the pores 24 of the core 20 (outer end surface 22a). The third magnetic particles 39 may have an average particle size that allows them to enter the pores 24 of the core 20. The core 20 may have pores 24 with a minimum diameter (the minimum length of a straight line connecting two points on the outer edge of the pore 24 in the cross section of the pore 24) that is larger than the average particle size of the first magnetic particles 37 or the third magnetic particles 39. The minimum diameter of the pore 24 is not particularly limited, but is, for example, larger than 10 μm. Resin may enter the pores 24 together with the first magnetic particles 37 and / or the third magnetic particles 39.

[0083] The average particle size of the magnetic particles (first magnetic particle 37, second magnetic particle 38, or third magnetic particle 39) can be calculated by measuring the maximum diameter of multiple magnetic particles (the longest length of a straight line connecting two points on the outer edge of a magnetic particle in the cross section of the magnetic particle) as the particle size in an SEM or STEM image of the cross section of the outer casing 30, and calculating the arithmetic mean value (number average) of the measured diameters as the average particle size. However, a method may also be used in which the SEM or STEM image of the cross section of the outer casing 30 is subjected to image analysis to determine the particle size distribution, and the particle size at which the integrated value reaches 50% (D50, median diameter) is used as the average particle size.

[0084] In this embodiment, in the YZ cross section of the exterior body 30, the area proportion of magnetic particles having a small average particle size is higher in the covering portion 32 (covering portions 32a, 32b and / or 32c) than in the main body portion 31. In particular, the area proportion of magnetic particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b is higher in the covering portion 32 than in the main body portion 31. Furthermore, the area proportion of magnetic particles having an average particle size smaller than the thickness (average thickness or minimum thickness) of the covering portion 32 (covering portions 32a, 32b or 32c) is higher in the covering portion 32 than in the main body portion 31.

[0085] For example, the area ratio of the first magnetic particles 37 is higher in the covering portion 32 than in the main body portion 31. The area ratio of the total of the first magnetic particles 37 and the third magnetic particles 39 (however, particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b) may be higher in the covering portion 32 than in the main body portion 31.

[0086] The area ratio of the first magnetic particles 37 in the coating portion 32 is not particularly limited, but may be, for example, 50% or more, 60% or more, or 70% or more. On the other hand, the area ratio of the second magnetic particles 38 in the coating portion 32 is not particularly limited, but may be, for example, 10% or less or 5% or less. The total area ratio of the first magnetic particles 37 and the third magnetic particles 39 in the coating portion 32 is not particularly limited, but may be, for example, 50% or more, 60% or more, 70% or more, or 80% or more.

[0087] In the coating portion 32, the area proportion of the first magnetic particles 37 is the highest, and the area proportion of the second magnetic particles 38 is the lowest. In the example shown in Fig. 7, the area proportion of the second magnetic particles 38 in the coating portion 32 (coating portions 32a, 32b and / or 32c) is substantially 0%. In the coating portion 32, the area proportion of the third magnetic particles 39 may be lower than the area proportion of the first magnetic particles 37 and higher than the area proportion of the second magnetic particles 38.

[0088] The area proportion of the magnetic particles (first magnetic particles 37, second magnetic particles 38 or third magnetic particles 39) can be measured by observing the cross section of the outer casing 30 with a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM), binarizing the obtained cross-sectional image, and performing image analysis to determine the area proportion occupied by the magnetic particles relative to the entire image of a specified area (e.g., unit area).

[0089] In this embodiment, in the YZ cross section of the exterior body 30, the area proportion of magnetic particles having a small average particle size is higher in the covering portion 32 (covering portions 32a, 32b and / or 32c) than in the peripheral portion 33. In particular, the area proportion of magnetic particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b is higher in the covering portion 32 than in the peripheral portion 33. Furthermore, the area proportion of magnetic particles having an average particle size smaller than the thickness of the covering portion 32 (covering portions 32a, 32b or 32c) is higher in the covering portion 32 than in the peripheral portion 33.

[0090] For example, the area ratio of the first magnetic particles 37 is higher in the covering portion 32 than in the peripheral portion 33. The area ratio of the total of the first magnetic particles 37 and the third magnetic particles 39 (however, particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b) may be higher in the covering portion 32 than in the peripheral portion 33.

[0091] Next, a method for manufacturing the coil device 1 will be described. First, the core 20 shown in FIG. 3 is prepared. Next, the terminal electrodes 40a and 40b are formed on the flange portion 22 by a paste method, plating method, sputtering, screen printing, or the like. Next, the winding portion 11 is fitted into the core portion 21. Alternatively, the wire 10 is wound around the core portion 21. Next, the lead portion 12a is connected to the terminal electrode 40a, and the lead portion 12b is connected to the terminal electrode 40b.

[0092] Next, a release sheet is placed in a mold (not shown), and the core 20 shown in FIG. 3 is placed in the mold so that the surfaces of the terminal electrodes 40a and 40b abut against the release sheet. Next, the exterior material (first magnetic particles 37, second magnetic particles 38, and third magnetic particles 39) that constitutes the exterior body 30 is filled into the interior of the mold. As a result, the core portion 21, the wound portion 11, and the flange portion 22 are covered with the exterior material. The exterior material also fills the space between the release sheet and the outer end surface 22a of the flange portion 22. As a result, the outer edges of the terminal electrodes 40a and 40b are covered with the exterior material. The exterior material also fills the inter-electrode region 35 (FIG. 4), and the inter-electrode region 35 is partially covered with the exterior material.

[0093] Next, the exterior material is compressed and hardened at a predetermined temperature for a predetermined time. This forms the element body 2 (FIG. 1). More specifically, the exterior material covering the core portion 21, the winding portion 11, and the flange portion 22 becomes the main body portion 31 shown in FIGS. 5 and 6. The exterior material covering the outer edges of the terminal electrodes 40a and 40b becomes the covering portion 32c (32) shown in FIG. 5. The exterior material covering the inter-electrode region 35 becomes the covering portions 32a and 32b (32) shown in FIG. 6. The outer edges of the first surface 30a (first outer edge portion 2b1, second outer edge portion 2b2, third outer edge portion 2b3, and fourth outer edge portion 2b4) form the peripheral edge portion 33 shown in FIG. 4.

[0094] The size, shape, formation range, etc. of the covering portions 32a to 32c shown in Figure 4 can be adjusted depending on conditions such as the amount of sheath material that wraps around the inter-electrode region 35, the pressure when the sheath material is compressed, the types of magnetic particles and resin that make up the sheath material, the size of the mold, and the arrangement of the core 20 in the mold.

[0095] 7, the second magnetic particles 38 have a relatively large particle size and therefore cannot enter the space between the release sheet and the outer end surface 22a of the flange 22. On the other hand, the first magnetic particles 37 and / or the third magnetic particles 39 have a relatively small particle size and therefore can enter the space between the release sheet and the outer end surface 22a of the flange 22. Therefore, in the cross section of the exterior body 30, the area proportion of magnetic particles having a small average particle size is higher in the covering portion 32 (covering portions 32a, 32b and / or 32c) compared to the main body portion 31. In this manner, the coil component 1 can be obtained.

[0096] 5 and 6 , in the coil device 1 of this embodiment, the exterior body 30 has a main body portion 31 that covers at least the core portion 21 and the winding portion 11, and a covering portion 32 that protrudes from the outer end surface 22a of the flange portion 22 and overlaps with the outer end surface 22a when viewed in the axial direction of the core portion 21. Because the covering portion 32 covers the outer end surface 22a of the flange portion 22, it serves as a stopper (a retainer) that fixes the core 20 to the main body portion 31. This increases the fixing strength (connection strength) between the core 20 and the exterior body 30, making the core 20 less likely to peel off from the exterior body 30.

[0097] 7 , in the coil device 1 of this embodiment, in the cross section of the outer casing 30, the area ratio of magnetic particles having a small average particle size is higher in the covering portion 32 (for example, the covering portion 32a) than in the main body portion 31. This makes it easier for the magnetic particles in the covering portion 32 to enter the irregularities 24 formed on the outer end surface 22a of the flange portion 22, and the covering portion 32 is fixed (connected) to the flange portion 22 via the magnetic particles that have entered the irregularities 24. This increases the fixing strength (connection strength) between the flange portion 22 and the covering portion 32, making it even more difficult for the core 20 to peel off from the outer casing 30.

[0098] The exterior body 30 also has a peripheral portion 33 that protrudes relative to the outer end surface 22a of the flange portion 22 and does not overlap with the outer end surface 22a when viewed in the axial direction of the core portion 21. In a cross section of the exterior body 30, the covering portion 32 has a higher area ratio of magnetic particles having a small average particle size than the peripheral portion 33. In this case, the area ratio of magnetic particles having a larger average particle size than the covering portion 32 is also higher in the peripheral portion 33 as well as in the main body portion 31. As a result, the area ratio of magnetic particles having a relatively large average particle size increases in the exterior body 30, and the inductance characteristics of the coil device 1 improve.

[0099] Furthermore, the core 20 is a sintered core having pores 24. Therefore, in the covering portion 32, magnetic particles enter the pores 24 (irregularities) of the outer end surface 22a, and the covering portion 32 and the flange portion 22 are fixed (connected) together via the magnetic particles that have entered the pores 24. This further increases the fixing strength (connection strength) between the flange portion 22 and the covering portion 32.

[0100] Additionally, the covering portion 32 contains magnetic particles having an average particle size that allows them to enter the holes 24. This makes it easier for the magnetic particles to enter the holes 24 in the outer end surface 22a, thereby further increasing the fixing strength (connection strength) between the flange portion 22 and the covering portion 32.

[0101] Furthermore, the surface roughness of the outer end surface 22a is smaller than the surface roughness of the covering portion 32. Therefore, solder, conductive adhesive, etc. are less likely to adhere to the surface of the covering portion 32. As a result, the covering portion 32 can prevent the solder, conductive adhesive, etc. from protruding from the terminal electrode 40a.

[0102] 4, the covering portion 32 is located at least in the inter-electrode region 35 between the first terminal electrode 40a and the second terminal electrode 40b. By forming the covering portion 32 in the inter-electrode region 35, the covering portion 32 and the flange portion 22 are fixed (connected) to each other at the center of the outer end surface 22a of the flange portion 22 (the center in the X-axis direction connecting the first terminal electrode 40a and the second terminal electrode 40b). This further increases the fixing strength (connection strength) between the flange portion 22 and the covering portion 32.

[0103] Second embodiment 8 and 9 has the same configuration as the coil device 1 of the first embodiment, except for the following points. The same reference numerals are used to designate parts that overlap with the coil device 1 of the first embodiment, and detailed descriptions thereof will be omitted.

[0104] As shown in FIG. 9, the coil device 1A includes a core 20A and an outer casing 30A. The core 20A includes a flange 22A. The flange 22A includes a chamfered portion 23. The chamfered portion 23 is formed on a ridge portion located between the outer end surface 22a and the side surface 22c. At the location of the chamfered portion 23, the outer end surface 22a is inclined relative to the inner end surface 22b, and the thickness of the flange 22A decreases toward the outer periphery of the outer end surface 22a. When the flange 22A includes the chamfered portion 23, a portion of the outer casing material constituting the outer casing 30 tends to extend from the outside of the side surface 22c of the flange 22A to a position below the height of the outer end surface 22a and further onto the terminal electrode 40a. Therefore, the covering 32c (FIG. 8) can indirectly cover at least a portion of the chamfered portion 23 while covering the outer edge of the terminal electrode 40a. In the example shown in Fig. 8, the surface of terminal electrode 40a is flat except for both ends of terminal electrode 40a in the X-axis direction. However, the shape of terminal electrode 40a may be the same as the shape of terminal electrode 40a shown in Fig. 5. The same applies to terminal electrode 40b.

[0105] The depth (maximum value) of chamfered portion 23 from outer end surface 22a of flange portion 22A is not particularly limited, but is, for example, 10 μm to 50 μm. The depth of chamfered portion 23 may be equal to or less than the thickness of terminal electrode 40a or 40b, or may be equal to or greater than the thickness of terminal electrode 40a or 40b.

[0106] The exterior body 30A has a covering portion 32A. The covering portion 32A (covering portions 32a, 32b, and / or 32c) has a small particle size region 320 and a large particle size region 322. The small particle size region 320 does not overlap with the chamfered portion 23 when viewed from the Z-axis direction (in the Z-axis direction). On the other hand, the large particle size region 322 overlaps with the chamfered portion 23 when viewed from the Z-axis direction (in the Z-axis direction). In the radial direction of the flange portion 22A (in the Y-axis direction in the example shown in FIG. 9 ), the small particle size region 320 is located more inward of the outer end surface 22a than the large particle size region 322.

[0107] In the YZ cross section of the outer casing 30A, the area proportion of magnetic particles having a large average particle size is higher in the large particle size region 322 than in the small particle size region 320. For example, the area proportion of the third magnetic particles 39 (particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b) is higher in the large particle size region 322 than in the small particle size region 320. The total area proportion of the first magnetic particles 37 and the third magnetic particles 39 may be higher in the large particle size region 322 than in the small particle size region 320.

[0108] In the YZ cross section of the exterior body 30A, the area proportion of magnetic particles having a small average particle size is higher in the small particle size region 320 and / or the large particle size region 322 than in the main body portion 31. In particular, the area proportion of magnetic particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b is higher in the small particle size region 320 and / or the large particle size region 322 than in the main body portion 31. Furthermore, the area proportion of magnetic particles having an average particle size smaller than the thickness of the coating portion 32 (coating portion 32a, 32b, or 32c) is higher in the small particle size region 320 and / or the large particle size region 322 than in the main body portion 31.

[0109] For example, the area ratio of the first magnetic particles 37 is higher in the small particle size region 320 and / or the large particle size region 322 than in the main body portion 31. The area ratio of the total of the first magnetic particles 37 and the third magnetic particles 39 (however, particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b) may be higher in the small particle size region 320 and / or the large particle size region 322 than in the main body portion 31.

[0110] In the YZ cross section of the exterior body 30A, the area proportion of magnetic particles having a small average particle size is higher in the small particle size region 320 and / or the large particle size region 322 than in the peripheral portion 33. In particular, the area proportion of magnetic particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b is higher in the small particle size region 320 and / or the large particle size region 322 than in the peripheral portion 33. Furthermore, the area proportion of magnetic particles having an average particle size smaller than the thickness of the coating 32 (coating 32a, 32b, or 32c) is higher in the small particle size region 320 and / or the large particle size region 322 than in the peripheral portion 33.

[0111] For example, the area ratio of the first magnetic particles 37 is higher in the small particle size region 320 and / or the large particle size region 322 than in the peripheral portion 33. The area ratio of the total of the first magnetic particles 37 and the third magnetic particles 39 (however, particles having an average particle size smaller than the thickness of the terminal electrode 40a or 40b) may be higher in the small particle size region 320 and / or the large particle size region 322 than in the peripheral portion 33.

[0112] In this embodiment, the same effects as in the first embodiment can be obtained. In addition, in this embodiment, as shown in Fig. 9, flange portion 22A has chamfered portion 23 formed on the ridge between outer end surface 22a and side surface 22c. Therefore, in the manufacturing process of coil device 1A, magnetic particles having a relatively small average particle size tend to flow toward outer end surface 22a of flange portion 22A through chamfered portion 23. This makes it easier to form covering portion 32A so as to overlap outer end surface 22a of flange portion 22A when viewed from the axial direction (Z-axis direction) of core portion 21.

[0113] The covering portion 32A has a small particle size region 320 and a large particle size region 322. The small particle size region 320 does not overlap the chamfered portion 23 when viewed in the axial direction of the core portion 21. The large particle size region 322 overlaps the chamfered portion 23 when viewed in the axial direction of the core portion 21. The large particle size region 322 has a higher area ratio of magnetic particles having a larger average particle size than the small particle size region 320. Therefore, not only in the main body 31 but also in the large particle size region 322, the area ratio of magnetic particles having a larger average particle size than the small particle size region 320 is higher. As a result, the area ratio of magnetic particles having a relatively large average particle size increases in the exterior body 30A, improving the inductance characteristics of the coil device 1A.

[0114] Furthermore, when magnetic particles having a relatively large average particle size are arranged at positions overlapping with chamfered portion 23 (positions corresponding to large particle size regions 322) during the manufacturing process of coil component 1A (the compression molding process of magnetic particles and resin), the following effect is obtained. That is, magnetic particles having a relatively small average particle size flow toward positions overlapping with outer end surface 22a of flange portion 22A (positions corresponding to small particle size regions 320), passing through between magnetic particles having a relatively large average particle size. This allows magnetic particles having a relatively small average particle size to be selectively arranged at positions overlapping with outer end surface 22a of flange portion 22A. This makes it easier to form small particle size regions 320 at positions overlapping with outer end surface 22a.

[0115] Furthermore, in the radial direction of flange 22A, small particle diameter region 320 is located more inward of outer end surface 22a than large particle diameter region 322. Therefore, inside outer end surface 22a, coating 32A and flange 22A are fixed (connected) via magnetic particles that have entered the irregularities. This further increases the fixing strength (connection strength) between flange 22A and coating 32A.

[0116] The present disclosure is not limited to the above-described embodiments and can be modified in various ways within the scope of the present disclosure. For example, as shown in Fig. 10, in each of the above-described embodiments, only the covering portion 32b may be formed in the inter-electrode region 35. Although not shown in detail, only the covering portion 32a may be formed in the inter-electrode region 35.

[0117] 11, in each of the above embodiments, the area of ​​the covering portion 32b may be larger than the area of ​​the covering portion 32a. Although not shown in detail, the area of ​​the covering portion 32a may be larger than the area of ​​the covering portion 32b.

[0118] 12, in each of the above-described embodiments, the covering portion 32 does not have to cover the terminal electrodes 40a and 40b. In the example shown in Fig. 10, the covering portion 32 is adjacent to the terminal electrodes 40a and 40b without overlapping them. The covering portion 32 is in contact with the terminal electrodes 40a and 40b along the X-axis direction, but may be spaced apart from the terminal electrodes 40a and 40b.

[0119] Furthermore, the peripheral edge 33 may directly cover at least a portion of the outer edge of the outer end surface 22a. In the example shown in Fig. 12, a portion of the peripheral edge 33 is located on the outer edge of the outer end surface 22a and overlaps with the outer end surface 22a.

[0120] 13, in each of the above embodiments, the covering portion 32 does not have to include the covering portion 32c and the peripheral portion 33. In the example shown in Fig. 13, the covering portions 32a and 32b are formed in the inter-electrode region 35 without being exposed to the outside of the inter-electrode region 35.

[0121] In each of the above embodiments, as shown in FIG. 7, the outer casing 30 contains magnetic particles having three different average particle sizes (first magnetic particles 37, second magnetic particles 38, and third magnetic particles 39), but it may also contain magnetic particles having two different average particle sizes, or it may also contain magnetic particles having four or more different average particle sizes.

[0122] In each of the above embodiments, as shown in FIG. 3, the core 20 is a T-shaped core, but it may be a drum core in which flanges 22 are formed on both axial ends of the core portion 21.

[0123] In each of the above embodiments, the winding portion 11 shown in FIG. 3 may be made of a rectangular wire wound edgewise or flatwise.

[0124] In each of the above embodiments, the winding axis direction of winding unit 11 shown in FIG. 3 may be parallel to first surface 30a.

[0125] In each of the above embodiments, the embedded portions 44 and 46 may be omitted from the terminal electrode 40a shown in Fig. 3. The same applies to the terminal electrode 40b.

[0126] In each of the above embodiments, the core 20 shown in FIG. 3 does not have to be a sintered body, and may be formed from the same material and by the same manufacturing method as the outer casing 30. [Explanation of symbols]

[0127] 1,1A...Coil parts 2...Base body 2b1 to 2b4: First outer edge to fourth outer edge 10...Wire 11... Winding section 12a, 12b…Drawer part 20,20A...Core 21…core part 22,22A…Tsubabe 22a...Outer end surface 22b…Inner end surface 22c...side 23... Chamfered part 24...Vacancy 30, 30A...Exterior body 30a~30f...1st side~6th side 31...Main body 32, 32A, 32a, 32b, 32c...coated portion 320…Small particle size area 322...Large particle size region 33...periphery 35…Inter-electrode area 36a, 36b…electrode contact part 37...first magnetic particle 38…Second magnetic particle 39…Third magnetic particle 40a,40b…terminal electrode 41a1, 41a2, 41a3, 41a4, 41b1, 41b2, 41b3, 41b4...1st side to 4th side 42...Exposed part 44, 46...Buried section

Claims

1. a core having a core portion and a flange portion formed at one end in the axial direction of the core portion; a wire having a winding portion provided on the core; an outer casing including magnetic particles having different average particle sizes and a resin; the exterior body has a main body portion that covers at least the core portion and the winding portion, and a covering portion that protrudes from an outer end surface of the flange portion and overlaps the outer end surface when viewed in the axial direction, A coil component in which, in a cross section of the exterior body, the covering portion has a higher area ratio of the magnetic particles having a smaller average particle size than the main body portion.

2. the exterior body has a peripheral edge portion that protrudes from an outer end surface of the flange portion and does not overlap with the outer end surface when viewed in the axial direction, The coil component according to claim 1 , wherein in a cross section of the exterior body, the magnetic particles having a small average particle size have a higher area ratio in the covering portion than in the peripheral portion.

3. 3. The coil component according to claim 1, wherein the flange portion has an inner end surface facing the outer end surface along the axial direction, a side surface connecting the inner end surface and the outer end surface, and a chamfered portion formed on a ridge portion between the outer end surface and the side surface.

4. the coating portion has a small particle size region and a large particle size region, the small particle size region does not overlap with the chamfered portion when viewed from the axial direction, the large grain size region overlaps with the chamfered portion when viewed in the axial direction, The coil component according to claim 3 , wherein the area ratio of the magnetic particles having a large average particle size is higher in the large particle size region than in the small particle size region.

5. The coil component according to claim 4 , wherein the small grain size region is located more inwardly of the outer end surface than the large grain size region in the radial direction of the flange portion.

6. The coil component according to claim 1 or 2, wherein the core is a sintered core having pores.

7. The coil component according to claim 6 , wherein the coating contains the magnetic particles having an average particle size that allows the magnetic particles to enter the pores.

8. The coil component according to claim 1 , wherein the outer end surface has a surface roughness smaller than that of the covering portion.

9. The coil further includes a first terminal electrode and a second terminal electrode provided on at least the outer end surface, the wire has a first lead portion drawn from the winding portion and connected to the first terminal electrode, and a second lead portion drawn from the winding portion and connected to the second terminal electrode, The coil component according to claim 1 , wherein the covering portion is located at least in an inter-electrode region between the first terminal electrode and the second terminal electrode.

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